Fuse



Jan. 4,, 1949. r H. J. NICHOLS FUSE Filed April 14, 1943 w W z Patented Jan. 4, 1949 'U N l TED S TATES FPATE N T FF! CE 12458405 FUSE Harry J. Nichols, New York, N. Y.

Application April 14, 1943, Serial No. 483,027

11, Claims. 1

Thisinvention relates topoint detonating fuses especially designed for small aircraft and antiaircraft projectiles for automatic cannon, and :Will be described with relation to such application although it is to be understood that without material modification many features are equally. applicable for other uses.

Detonating fuses'for small projectiles forautomatic cannon, in calibresofZO mm. 0040 mm., inclusive, present .particulardifficulties because of their small size. and the great accelerating and centrifugal forces towhichthe mechanism is subjected when fired. in the gun, during flight, and on impact with the target. They must containa relatively large .detonator capable-of producing high-order detonation of relativelyinsensitive explosives, yet at the same time theymustbeentirely safe in storage, handling, andifiring,

In generaLfusesof .thisxtype-are required toibe (1) simple in designanduoperation, 1(2) easy-to manufactureandload, (3) free fromldeterioration in storage, i) safe in. handlingand using, and (5) certainin action.

.fusesweregenerally requiredto be highly sensitiveso as to explode instantlyon striking the flimsiest-part of an. airplane orxeven the fabricof .a'balloomthe. great increasein the size of .:air-' .planesendthe introduction of aircraftarmor, often in multiplelayers, has necessitated a. fuse action which differentiates .between light and heavy obstacles, .and which usually produces a slight delay in the burst, soas to produce the greatest effect behind any protective covering vor again-stxthe skeletal parts ofthe airplane.

Itisthereforcone of the principal objects of thisinventionito meet the. general. and particular In. particular, becauseiof thegreat forc'e'of acceleration or set-back" onfiring'. amounting to approximately 75,000 times the .weightoi -any component fuse: part in the case of120 mmscannon, the detonatorimay be. explodedby this: great force of concussion. .This possibilitymakes a detonator-safe feature. highly. desirable. feature assures that intheevent Jthe detonator is exploded by heat oraccident beforefiring. orzin the bore of the gun on firing, the explosion will be so limited as not to disrupt thewfuse, :norto cause break-up nor explosionof .the'projectile.

,Since a. relatively strong retarding force dueato the air resistance .acts on the projectile as it emerges from the. muzzlezof .thegun, and also since the projectile may simultaneously strike a weather seal or-other .lightprotective cover, or even some partof .the. plane insomecases, a muzzle-safe feature is. also.high1y. desirable. In other words, the fuse mustbszso constructedthat it will be safe against exploding while in the gun and for a short distance beyond the muzzle. of the gun.

During flight, the projectile. rotates atxgreat speed, exceeding 100,000'R. PxMzjn thecase of mm. cannon. Therefore, each-component 'of the fuse should be. dynamically balancedwith-respect to the. axis of rotation in orderto avoid unbalance whichemight causefailure of the fuseto function, or destroy the. ballisticstabilit'y of the. projectile in flight.

. Whereas prior. .to World! War 11; anti-aircraft This requirements-above stated in ahighly eficient, reliable, and practical Jnanner.v

:Afurther objectristoprovide a. fuse of the above character having relativelyfewparts which may ,be. inexpensively manufactured and assembled.

Afurther objectisto'provide,afuse of thela'stmentioned character which will [be detonatorsafe, bore-safe and muzzle-safe.

A further object is to ;provide.:a fuse .of :the abovecharacter adapted to functionor" explode the main charge: at different relative times .with respect touthei nature of thetarget beingihit,

Other objectswill be int'part jobvious from the annexed drawings and in part hereinafter .indicatedin'the description of thiszinvention.

mIn the:drawingsforminggpart of thisdisclosure, like'characte'rs-of referencedenote corresponding .parts throughout the several views, in which-- Fig. lwshows :in;.1ongiudina-1 cross-section en- ;l-agrged several times, alpoint-impact d'etonating iuse'especially :fori20 mm. projectilesillustrating .one embodiment-of theinvention, the mechanism beingshoWn-in'unarmed position, that is,.:normal safe position;

Fig.2 shows the same fusein the same section .asin Fig. Lthe-mechanism being shown in firing position, that is, whilein-ithe bore of. the gun during firing therefrom;

Fig. 3 shows the same ,fuse'in the same section. but with thexinechani'sm in' position .of night .after firing;

Fig. 4 is a transverse cross section ofjthe .fuse shown'in Fig. 3,-the section being taken at the plane indicated by 1-4 in Fig. 3;

Fig. 5'is a longitudinal section of the same fuse, but with the mechanism inthe position of impact with a relativelylight target; and

Fig. 6 is a longitudial section of the same fuse with the mechanism in the act of exploding the detonator.

. Referringnow to these drawings, and particularly to Fig. 1, the mainstructural-imemberiof the fuse is the body ID of conical contour and with external screw threads for assembly to the projectile (not shown).

The forward portion of the body I is provided with a cylindrical bore H in the axis of which the firing pin I2 is retained in the position shown by a bodily movable helical combined safety and firing spring |3 which bears against a small circular bead or detent means l4 formed near the mid-section of the firing pin l2. In the base of the body !0 is a main cylindrical bore adapted to receive the rotor housing l5 which is securely held in place at assembly by a spun-over position against displacement by any extraneous force or forces. The need for rotor locking detents and the like, typical of prior art, is thus avoided, and the rotor is in effect self-locking in armed position.

Referring again to Fig. l, the firing spring I2 is assembled partly compressed between the end of the bore II and the bead M on the firing pin, thus maintaining the point of the firing pin securely in the tapered hole 22 in the rotor 20, this being the same identical relative position to the fuse body as it is in exploding position, as shown lip I6 formed from the body as shown, or by a threaded connection if desired.

The rotor housing I5 has a rectangular crossslot H which rotatably supports edgewise therein a round safety rotor 20, shown in transverse section in Fig. 4, so that its axis of rotation crosses the axis of the fuse at right angles. This rotor has a diametrical bore in its equatorial plane adapted to receive a detonator 2| (preferably sealed in a thin metal capsule), and one or more small tapered holes 22 located on the equator at an angle of say 60 to the axis of the detonator hole. The point of the firing pin l2 extends into one of the tapered holes 22 to retain the rotor so that the detonator 2| is normally positioned obliquely, so as to be masked from the firing pin l2 and in safe relation to the lead-out hole or recess 23. The rotor is of special centro-symmetric form, that is, the rotor is substantially symmetrical with respect to its center of gravity and to the axis of the diametrical bore. The

preferred form is a sphere with two diametrically opposite and equal, parallel ends. The rotor thus has a form and structure which makes the detonator axis a, principal axis passing through its center of gravity, so that while it is virtually statically balanced as it lies obliquely in the hous-jing, it is dynamically unbalanced with respect to the axis of the fuse which is also the axis of rotation of the projectile. But when the detonator is rotated into alignment with the axis of the fuse as in Fig. 3, the rotor is dynamically balanced with respect to that axis. The rotor can also take the form of a short cylinder.

Referring to Fig. 4, it is seen that a diametrical channel 24 is formed in each end of the rotor,

these channels extending substantially parallel to the axis of the detonator hole 2|. Equal diametral centrifugal masses 25 are thus provided on each end of the rotor which masses upon rotation of the fuse about its axis produce a centrifugal torque-couple tending to rotate the rotor 20 countor-clockwise to bring the detonator 2| into alignment with the axis of the fuse. There may also be a minor centrifugal torque due to a difference in specific gravity of the detonator and the rotor metal which it displaces, but this minor torque is generally ineffective to turn the rotor if there is any eccentricity of rotation, such as occurs due to the yaw of the projectile in flight. The torquecouples due to the centrifugal masses tend automatically to compensate for minor eccentricity in flight due to yaw. Hence, the centrifugal masses may be considered to produce the torque effect which turns the detonator into armed position as shown in Fig. 3. Once in this position, the torquecouples combine to hold the rotor in a dynamically stable condition with the detonator in alignment with the fuse axis. Thus, when the rotor turns into armed position in response to centrifugal force, the same force and the restraint of the rotor housing positively maintains it in armed I into armed position while this force is acting.

in Fig. 6. Since the rotor normally has no par jticular tendency to turn out of position, the firing point suffices to hold the rotor 20 securely in position against accidental displacement, even when subjected to jolting and umbling tests. Thus, it is evident that the invention provides a fuse arming mechanism of extreme simplicity but of great security.

Referring now to the figures in sequence, the operation of the fuse mechanism is as follows:

In Fig. l the parts are shown in the position in which they are assembled, and the detonator 2| is maintained in safe position as described above. On firing in a gun, the condition of the fuse mechanism becomes that shown in Fig. 2, in which set-back has caused the firing spring i3 to slide bodily downwards over the bead M on the firing pin to the opposite end of the chamber H. The great force of set-back, which may amount to as much as 70,000 times the weight of the spring, fully compresses the spring I2 below the bead l 4 as shown. It is to be noted that the same powerful set-back holds the firing point of pin |2 securely in the hole 22 in the rotor 20 preventing any possibility of the rotor turning the detonator In the event of coppering or other obstructions in the bore of the gun capable of reversing the acceleration of the projectile, the firing pin [2 might be propelled forwards, but the effect of momentary reversal of acceleration on the rotor would be to hold it in unarmed position as shown.

When the projectile emerges from the muzzle of the gun, the firing spring l3 lifts the firing pin |2 forwardly, thereby freeing the rotor 20 which shortly thereafter turns about its axis to bring the detonator 2| into armed position as shown in Fig. 3. Meanwhile, before the detonator is completely armed, the projectile has proceeded many feet beyond the muzzle of the gun, thus clearing any nearby obstructions which might explode the projectile prematurely.

It will be evident from the above description of the functioning of the fuse during firing from the gun that the detonator does not become armed until the projectile has passed well beyond the muzzle of the gun, hence the fuse is detonator-safe, bore-safe" and muzzle-safe.

During flight the fuse continues in the condition shown in Fig. 3 until an obstacle is encountered, whereupon the type of action Will depend upon the solidity of the obstacle, First should this obstacle be thick armor, a heavy structural member, or like massive structure, capable of defeating the projectile, the point of the fuse will be driven inwardly, stabbing the firing pin 2 into the detonator 2| to produce an instantaneous burst of the projectile. As a second alternative, should the obstruction be of medium solidity penetrable by the projectile, such as thin armor or so-called burster plate, the firing spring l2 will slidebodily back over the ring or bead l4 into the position shown in Fig. 5, and

E5 on emergence of the projectile afterwpenetrating the. obstruction, the then cocked :firing spring l4 will drive the firingpin '12 intothe detonator': as shownin Fig. fi'to produce'a:short-delayburst.

@As a third alternative; should thefirst obstacle encountered be :quite thin, such as the skin: of a plane foriexample, then the percussion force acting-on the firing spring will not suffice tocause Y the firing spring 12 to slip backoverzthe fring'or bead I l and the spring --will prevent the firing pin [2 from bouncing back due to the-shock of impact, -h'ence fuse-action will not 'occu-r until a more substantial obstruction is encountered. This third-alternative action is specifically designed to I defeat "the so-called burstefiplate protection by delaying the fuse action until' after penetration of the main armor.

"-To summarize, the triple-action fuse of the invention provides first an instantaneous I burston heavy impacts likely to defeat the projectile; second, a-bu-rstafter-a-shor-t delay on medium armor and solid obstructions; and-third, on very thin armor such as --burster-plate, fuse action is suppressed until-a'more substantial obstruction is hit. These three alternative fuse actions'are obtained by a verysimple mechanism, thereby avoiding the complex mechanisms-of fuses of the prior are which provide automatic alternative action dependent upon the nature of the target.

It shouldbe evident from the foregoing that .the invention provides :novel and advantageous features in fuses and that-:tnewinvention as a whole, while simple in form, meets the complex general and special requirements for fuses of this class in a highly efficient .and practical manner.

7 I claim: I

1. In a fuse of the class described, a fuse body and safety arming and automatic delay action exploding mechanism therein comprising, in combination, an axially slidable fi-ring pin normally mounted'in exploding position, saidfiring pin having means near its mid-section for sustaining the thrust of a spring, spring means mounted co-axially with said firing pin for normally exerting pressure thereon to maintain said firin pin in exploding position, and for moving the firing pin to armed position after firing in a gun, a detonator, a centrifugal rotor carrying said detonator and normally maintained in unarmed position by said firing pin, and means including said spring and said firing pin for automatically delaying the explosion of said detonator until after penetration of armor defeated by the projectile, While permitting instananeous explosion of said detonator on encountering armor likely to defeat the projectile.

2. In a fuse of the class described, in combination, a fuse body adapted for mounting in the nose of a projectile including a firing pin bore and a rotor chamber; a substantially cylindrical firing pin having a point at one end and detent means near its mid-section positioned axially in said bore; a centrifugal rotor carrying a detonator in safe position rotatably mounted in said chamber; and a helical spring coiled about said firing pin and coacting with said detent means normally for holding said firing pin in safe position in retaining engagement with said rotor, and after set-back for moving said firing pin to armed position thereby releasing said rotor.

3. In a fuse of the class described, in combination, a fuse body adapted for mounting in the nose of a projectile and having a firing pin bore and a rotor chamber, a firing pin with detent means near its mid-section axially slidable in said ibore;aracientrifugala rotoriwith 2a detonator: in'isaife Pposition rotatably: mounted in? said chambentand a helical spring r'coiled about the:forwardposition :of said firing pint-and-normallyxcoacting :with said Idetent :means to. hold said firing "pin iniun- 'armed:.- position and adapted upon set-z-back 'to slide bodily rover said detent means to: the .xre'arward portionof said; firing. pin thereafterto move said firing pinto armedpositionand upon impact withastarget to return to .its :original. position and thereafter to force said firing pininto :Jex-

i ploding'engagement withqlthe detonator.

. Ina fuseroftthe class described, inzcombination, :fuse body: adapted for v:m-ounting :in'q the c nose of: a .projectilewandhaving a firing 'pin 2 bore and a rotor-chamber, a substantially: cylindrical pointed firing spin "axially slidable in said; bore;- a centrifugal detonator holder-with adeton'ator in -safe=position moun'tjedin saidschamber, a helical ispring coiled around the forward portion of -said firing pin, and detent means positioned nearthe mid-section of said firing pin with which said spring coacts normally to holdssaid .firing pin in unarmed position and over :which ;said :spring moves bodilyat set back toa compressedposition around the rearward portionof said firing pin.

5. .In a fuseof theclass described, .in combination, a fuse body adapted for mounting ain -the nose of .aprojectile .andhavinga firing pin. bore and a rotor chamberaapointedifiring pin' having ,pin in retaining engagement with :said rotor until the fuse is .fired in a x gun, for. thereafter moving u saidifiring 'pin Iinto armed "position, :and upon impact of the fuse with a'target for causing. said firing pin-to explode saiddetonator-after penetration of-said target.

6. In a fuse of the class described having a fuse body adapted for assembly to a rotative projectile and detonating means housed therein, in combination, an axially slidable firing pin having a spring support member and a firing point adapted to explode a detonator, a cylindrical detonator, centrifugally actuated safety means for carrying said detonator normally in unarmed position with its axis oblique to the axis of the fuse body and for rotating said detonator into armed position after the projectile is fired in a rifled gun comprising a rotor carrying said detonator in a diametrical bore and having means for producing a centrifugal torque couple exceeding any rotary effect due to said diametrical bore, safety means for said rotor including said firing pin, and safety means for successively retaining, arming, and propelling said firing pin comprising a compression spring coacting with said support member carried by said firing pin.

7. In a fuse of the class described, in combination, a fuse body adapted for mounting in the nose of a projectile for rifled cannon, firing and detonating means in said body including an axially slidable detonator firing pin and a movable cylindrical detonator normally carried in safe position obliquely to the axis of the fuse body, centrifugally actuated detonator arming means comprising a rotor concentrically mounted in said body and carrying said detonator in said safe position in a diametrical hole therein; and combined safety, arming, and firing means operatively connected with said firing pin, comprising a compression spring surrounding said firing pin in part and adapted to act thereon normally to hold said firing pin in detaining engagement with said rotor and after firing to arm said firing pin and after impact with a target to propel said firing pin into exploding relation with said detonator.

8. In a fuse of the class described, in combination, a fuse body and safety arming and delayedaction exploding mechanism therein comprising; an axially slidable firing pin having a spring support member and a firing point adapted to explode a detonator, said firing point being assembled in detonator exploding position in retaining engagement with a rotor; a firing spring mounted coaxially on said firing pin in compression between said support member and said body for retaining said firing point in detonator exploding position and for moving said firing pin to armed position after firing in a gun; a centrifugal rotor carrying a detonator normally held in unarmed position by said firing point and adapted to rotate said detonator into armed position after firing in a gun and upon release by said firing point; the aforesaid firing spring also being adapted to return said firing point forcibly from armed position to exploding position upon penetration of the target.

9. In a fuse of the class described, in combination, a fuse body adapted for mounting in the nose of a rotative projectile and having an axial firing pin bore and a rotor chamber, a firing pin having a detonator firing point and a bead near its mid-section mounted axially slidable in said bore, a centrifugally actuated rotor having a detonator mounted in a diametrical cavity therein rotatably mounted in said chamber and normally retained in unarmed position by said firing point, and combination safety and arming means for said firing pin comprising a compression spring coacting with the aforesaid bead to retain said firing pin in unarmed position, and characterized 8 by being adapted to slide bodily over said. bead when the projectile is fired and thereafter to move the firing pin to armed position.

10.- In a point detonating fuse having a fuse body adapted for mounting in the nose of a projectile and detonating means therein; the combination of a firing pin having a firing point adapted to explode a detonator, a stem, and a spring supporting bead on said stem; and a combination safety, arming, and propelling compression;spring adapted to coact with said bead on said 'firing pin normally to hold said firing pin in safeposition, after firing to move said firing pin to armed position, and after penetrating a target to propel said firing pin to detonator exploding position.

11. In a point detonating fuse having a fuse body adapted for assembly to the'nose of a projectile and firing mechanism therein, the combination of a firing pin having a stem with a spring detaining element thereon; and a compression spring mounted axially slidable on said stem so as normally to coact with said detaining element to maintain said firing pin in assembled position, on firing in a gun to slide bodily over said detaining element, and thereafter to move said firing pin to an operative position.

HARRY J. NICHOLS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,229,669 Stuart June 12, 1917 FOREIGN PATENTS Number Country Date 837,467 France Nov. 12, 1938 r 257,335 Great Britain Aug. 27, 1926 

